EP1536110A1 - Filtre à particules comportant une couche catalytique pour gaz d'échappement - Google Patents
Filtre à particules comportant une couche catalytique pour gaz d'échappement Download PDFInfo
- Publication number
- EP1536110A1 EP1536110A1 EP03104385A EP03104385A EP1536110A1 EP 1536110 A1 EP1536110 A1 EP 1536110A1 EP 03104385 A EP03104385 A EP 03104385A EP 03104385 A EP03104385 A EP 03104385A EP 1536110 A1 EP1536110 A1 EP 1536110A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- inlet
- channels
- catalyst
- soot filter
- outlet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
- F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
- F01N13/0097—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series the purifying devices are arranged in a single housing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/022—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
- F01N3/0222—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous the structure being monolithic, e.g. honeycombs
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2250/00—Combinations of different methods of purification
- F01N2250/02—Combinations of different methods of purification filtering and catalytic conversion
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2330/00—Structure of catalyst support or particle filter
- F01N2330/06—Ceramic, e.g. monoliths
Definitions
- the present invention generally relates to engine exhaust gas treatment and more particularly to the filtering of soot particulates from diesel engine exhaust gas using a catalysed filter.
- soot filters also commonly referred to as diesel particulate filter, particulate trap, soot catcher or bare trap
- a soot filter typically comprises a plurality of inlet and outlet channels separated by porous walls. The exhaust gas is forced to flow from the inlet channels to the outlet channels through the porous walls, so that the unburned soot particulates are retained in the pores of the lateral walls, and accumulate and form a porous layer on the inner surfaces of the channel walls.
- the biggest technical problem to be solved for continuous and reliable duty of a soot filter and of the upstream-located engine is to remove the soot particulates collected in the filter as they generate an excessive backpressure. Soot can be nearly totally eliminated when it is burned. This operation is commonly referred to as "filter regeneration” and has to be performed regularly.
- the soot particulates (mainly carbon) in contact with the oxygen in the exhaust gas are converted into CO and CO 2 during their combustion. This reaction only occurs at about 600°C, which are much higher than those at the soot filter inlet during normal operating conditions in most engines. Nevertheless, this combustion method has an industrial application in two major categories of soot filters.
- a first category is based on a fuel borne additive, which acts as a catalyst to reduce the regeneration initiation temperature by approximately 50-100°C. Hence, the catalyst provides a combustion initiation at about 500-550°C.
- a regeneration operation is started.
- the exhaust gas temperature is artificially increased up to its possible maximum value (by e.g. late or post injection and/or reduction of intake air), which is high enough to obtain the ignition and the combustion initiation of the collected soot particulates contai n-ing the fuel additive.
- this first category of soot filters involves increased complexity and maintenance, and thus high costs.
- the catalyst is provided directly in the filter.
- US 5,100,632 describes such a catalysed soot filter, wherein a catalyst blend is present on the porous filter walls in the form of a coating or a film layer.
- the catalyst blend consists of a mixture of one or more platinum group metals and one or more alkaline earth metal oxides. The presence of this catalyst blend in the filter lowers the temperature at which ignition and incineration of the particulates collected on the filter walls may be effected so that continuous self-cleaning or regeneration of the filter can be accomplished at diesel exhaust temperatures encountered under certain engine operating conditions.
- catalysed soot filters do not necessarily use the catalyst blend of US 5,100,632, and may provide the supplementary energy needed for soot particulates ignition and combustion initiation with other catalytic blends or exhaust gas temperature increase cycles performed regularly (mainly with the engine management system).
- the object of the present invention is to provide a less expensive catalysed soot filter with excellent catalytic and filtering performances. This object is achieved by a catalysed soot filter as claimed in claim 1.
- a catalysed soot filter in accordance with the invention comprises a filter body having a plurality of inlet channels and outlet channels separated by porous walls and arranged so that particle-laden gas to be filtered is forced to flow from the inlet channels to the outlet channels through these porous walls.
- a catalyst coating is applied in the inlet channels on the porous walls. Such a catalyst coating is typically used to reduce the activation energy of the soot combustion reaction; or in other words to lower the ignition and combustion temperature of particles accumulating thereon. According to an important aspect of the invention, the catalyst coating is applied in such a way that the inlet channels comprise at least two channel portions with a different catalyst content.
- the catalysed soot filter of the invention thus does not have a fixed catalyst content throughout the inlet channels, but comprises two (or more) channel portions with differing catalyst contents. This allows to play on the catalyst content at different locations in the filter and namely to reduce the catalyst content where it is not (or less) necessary. This is more particularly the case in the rear or downstream portion (with regard to the flow direction of the gases) of the inlet channels. Indeed, these downstream portions of the inlet channels tend to get rapidly clogged by unburnable particles (e.g. mineral ashes), which reduces the length of the inlet channels and causes gases to flow into the outlet channels via the porous walls further upstream of this clogged portion. Therefore, since this part of the filter will rapidly become ineffective, one may reduce the catalyst content in these downstream portions of the inlet channels. As a result, the upstream portions of the inlet channels shall advantageously have a greater catalyst content than the downstream portions.
- the downstream channel portion of each inlet channel has a catalyst content tending towards zero.
- the downstream channel portion of each inlet channel has a catalyst content equal to zero.
- the upstream portion represents between 60 and 90 % of the length of the inlet channel, more preferably between 70 and 80 %.
- the obtained filter performs as good as a conventional filter where the catalyst coating is uniformly applied over the whole length of the inlet channels.
- the catalyst coating is applied in each portion of the inlet channels in a controlled manner in accordance with the catalyst content to be provided in these portions. This means that the differences in catalyst content along the channels are not accidental (e.g. due to poor process controllability).
- the filter body preferably has an inlet side and an outlet side, and the inlet and outlet channels extend from the inlet side to the outlet side.
- the inlet channels are open on the inlet side for the particle laden exhaust-gas to enter the filter and the outlet channels are closed on the inlet side.
- the outlet channels are open on the outlet side for the filtered exhaust-gas to exit the filter and the inlet channels are closed on the exhaust side.
- each inlet channel is adjacent to a predetermined number of channels and each outlet channel is adjacent to the same predetermined number of inlet channels, except at the periphery of the soot filter.
- This predetermined number of channels is comprised between 3 and 6. Preferably, it is equal to 4 or to 6, in which case it forms a honeycomb structure.
- the catalyst coating it preferably comprises catalytic substances which permit to reduce the activation energy of the soot combustion reaction.
- a preferred catalytic coating comprises a mixture of at least one platinum group metal and at least one alkaline earth metal oxide.
- the catalyst coating is preferably uniformly applied in the upstream channel portion that a predetermined amount of catalyst is deposited.
- the present catalysed soot filtered is particularly suited to be used in diesel engines, it may be used in a variety of applications relating to the filtering of soot particles carried in a gas. In particular, it may also find application in the filtering of gasoline engine exhaust gas for future emission requirements.
- a method for manufacturing a catalysed soot filter comprises the steps of:
- the catalyst coating is applied in such a way that the inlet channels comprise at least two channel portions with a different catalyst content.
- the catalyst coating is preferably applied in such a way as to form an upstream channel portion having a greater catalyst content than a downstream channel portion.
- the downstream channel portion has a catalyst content equal to, or tending towards, zero.
- the upstream portion may have a length representing between 60 and 90 % of the length of said inlet channel, preferably between 70 and 80 %.
- the catalyst coating in the upstream channel portion can be applied by immersion in a solution containing the desired catalyst composition.
- Fig.1 shows a preferred embodiment of a soot filter 10 in accordance with the invention, which is disposed in a filter housing 12 including a diesel oxidation catalyst 14.
- the oxidation catalyst 14 is provided to oxidize CO and hydrocarbons in the exhaust gas under normal operation, and permits to increase the temperature of the exhaust gases in the filter regeneration mode with post injection.
- the filter 10 preferably includes a ceramic monolith body (made e.g. of SiC or cordierite) having a plurality of porous internal walls 16.
- the walls 16 define square cross-sectioned parallel passages, the alternate ends of which are plugged by end walls 18, 20 to define a plurality of adjacent inlet and outlet channels, 22 and 24 respectively.
- the inlet and outlet channels 22, 24, configuration is such that each inlet channel 22 is in communication with four outlet channels 24 via the porous walls 16, except at the periphery of the filter.
- the flow of exhaust gas arriving on the inlet side 26 will enter the inlet channels 22, flow into the outlet channels 24 through the porous channel walls 16-whereby the soot particles deposit on the inlet channel walls-and exit the outlet channels 24 on the outlet side 28.
- the porosity of the porous walls 16 is selected so that most or all of the particles are restrained from passing through the filter with the gas, so that the filtered particulates collect on surfaces of the porous inlet channel walls. With time, soot particles (mainly carbonaceous material) accumulate on the inlet channel walls, which must undergo regeneration to burn these soot particles.
- the present filter 10 is provided with a catalyst coating or film (not shown in the drawings) in the inlet channels 22 in order to reduce the activation energy of the soot combustion reaction, so that the cleaning or regeneration of the particles collected on the filter walls can be effected at diesel exhaust gas temperatures encountered under certain engine operating conditions (in particular lower temperatures than those required for the fuel borne catalyst systems).
- the inlet channels 22 of the soot filter 10 are provided with a catalyst coating that has been applied in a controlled manner in such a way that there are two channel portions with a different catalyst content. More precisely, in the present embodiment, an upstream portion of the channel is coated with a catalyst coating having a predetermined catalyst content C1, whereas a downstream part of the inlet channels has a catalyst content equal to zero or tending towards zero. In other words, there is no (or almost no) catalyst coating on the downstream portion of the channels.
- the upstream portion corresponds to about 70 to 80% of the length of the inlet channels. This is indicated in Fig.1 by the arrow "U", which thus represents the front inlet channel portion having a catalyst coating, and the rear, downstream part without catalyst or with an insignificant amount of catalyst is indicated "D".
- the catalyst coating is applied by immersion in a solution containing the desired catalyst composition to a depth equal to the desired proportion of inlet channel length (about 75 % of the length of the inlet channels in Fig.1).
- a solution containing the catalyst may include e.g. a mixture of at least one platinum group metal and at least one alkaline earth metal oxide at a given concentration.
- the catalyst will thus deposit on the channel walls over a length corresponding to the upstream portion, and thereby form a catalyst coating (or film) with a certain amount of catalyst per surface unit.
- the catalyst coating is applied in a controlled manner to provide in each portion a catalyst content equal to a design value.
- this design value there may be small variations about this design value at two different locations of this channel portion.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03104385A EP1536110A1 (fr) | 2003-11-26 | 2003-11-26 | Filtre à particules comportant une couche catalytique pour gaz d'échappement |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03104385A EP1536110A1 (fr) | 2003-11-26 | 2003-11-26 | Filtre à particules comportant une couche catalytique pour gaz d'échappement |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1536110A1 true EP1536110A1 (fr) | 2005-06-01 |
Family
ID=34443055
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP03104385A Withdrawn EP1536110A1 (fr) | 2003-11-26 | 2003-11-26 | Filtre à particules comportant une couche catalytique pour gaz d'échappement |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP1536110A1 (fr) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008009346A1 (fr) * | 2006-07-15 | 2008-01-24 | Daimler Ag | séparateur de particules et procédé de régénération d'un séparateur de particules |
KR101290525B1 (ko) | 2007-05-10 | 2013-07-30 | 주식회사 에코닉스 | 연료함유촉매가 적용된 디젤 차량용 배기정화 시스템 및방법 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5089237A (en) * | 1989-07-20 | 1992-02-18 | Daimler-Benz Ag | Gas filter with catalytic coating and a gastight downstream region |
US5100632A (en) * | 1984-04-23 | 1992-03-31 | Engelhard Corporation | Catalyzed diesel exhaust particulate filter |
WO2001012320A1 (fr) * | 1999-08-13 | 2001-02-22 | Johnson Matthey Public Limited Company | Filtre catalytique a ecoulement sur paroi |
EP1300193A1 (fr) * | 2001-10-06 | 2003-04-09 | OMG AG & Co. KG | Procédé et dispositif pour la conversion des pollutants gaz eux contenus dans le gaz d'échappement des moteurs thermiques |
EP1312776A2 (fr) * | 2001-11-16 | 2003-05-21 | Isuzu Motors Limited | Système pour la purification de gaz d'échappement |
JP2003154223A (ja) * | 2001-07-18 | 2003-05-27 | Ibiden Co Ltd | 触媒つきフィルタ、その製造方法及び排気ガス浄化システム |
-
2003
- 2003-11-26 EP EP03104385A patent/EP1536110A1/fr not_active Withdrawn
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5100632A (en) * | 1984-04-23 | 1992-03-31 | Engelhard Corporation | Catalyzed diesel exhaust particulate filter |
US5089237A (en) * | 1989-07-20 | 1992-02-18 | Daimler-Benz Ag | Gas filter with catalytic coating and a gastight downstream region |
WO2001012320A1 (fr) * | 1999-08-13 | 2001-02-22 | Johnson Matthey Public Limited Company | Filtre catalytique a ecoulement sur paroi |
JP2003154223A (ja) * | 2001-07-18 | 2003-05-27 | Ibiden Co Ltd | 触媒つきフィルタ、その製造方法及び排気ガス浄化システム |
EP1300193A1 (fr) * | 2001-10-06 | 2003-04-09 | OMG AG & Co. KG | Procédé et dispositif pour la conversion des pollutants gaz eux contenus dans le gaz d'échappement des moteurs thermiques |
EP1312776A2 (fr) * | 2001-11-16 | 2003-05-21 | Isuzu Motors Limited | Système pour la purification de gaz d'échappement |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 2003, no. 09 3 September 2003 (2003-09-03) * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008009346A1 (fr) * | 2006-07-15 | 2008-01-24 | Daimler Ag | séparateur de particules et procédé de régénération d'un séparateur de particules |
KR101290525B1 (ko) | 2007-05-10 | 2013-07-30 | 주식회사 에코닉스 | 연료함유촉매가 적용된 디젤 차량용 배기정화 시스템 및방법 |
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